text: # Copyright 2009-present MongoDB, Inc.
  #
  # Licensed under the Apache License, Version 2.0 (the "License");
  # you may not use this file except in compliance with the License.
  # You may obtain a copy of the License at
  #
  # http://www.apache.org/licenses/LICENSE-2.0
  #
  # Unless required by applicable law or agreed to in writing, software
  # distributed under the License is distributed on an "AS IS" BASIS,
  # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  # See the License for the specific language governing permissions and
  # limitations under the License.
  
  """GridFS is a specification for storing large objects in Mongo.
  
  The :mod:`gridfs` package is an implementation of GridFS on top of
  :mod:`pymongo`, exposing a file-like interface.
  
  .. seealso:: The MongoDB documentation on `gridfs <https://dochub.mongodb.org/core/gridfs>`_.
  """
  
  from collections import abc
  from typing import Any, List, Mapping, Optional, cast
  
  from bson.objectid import ObjectId
  from gridfs.errors import NoFile
  from gridfs.grid_file import (
      DEFAULT_CHUNK_SIZE,
      GridIn,
      GridOut,
      GridOutCursor,
      _clear_entity_type_registry,
      _disallow_transactions,
  )
  from pymongo import ASCENDING, DESCENDING
  from pymongo.client_session import ClientSession
  from pymongo.collection import Collection
  from pymongo.common import validate_string
  from pymongo.database import Database
  from pymongo.errors import ConfigurationError
  from pymongo.read_preferences import _ServerMode
  from pymongo.write_concern import WriteConcern
  
  
  class GridFS(object):
      """An instance of GridFS on top of a single Database."""
  
      def __init__(self, database: Database, collection: str = "fs"):
          """Create a new instance of :class:`GridFS`.
  
          Raises :class:`TypeError` if `database` is not an instance of
          :class:`~pymongo.database.Database`.
  
          :Parameters:
            - `database`: database to use
            - `collection` (optional): root collection to use
  
          .. versionchanged:: 4.0
             Removed the `disable_md5` parameter. See
             :ref:`removed-gridfs-checksum` for details.
  
          .. versionchanged:: 3.11
             Running a GridFS operation in a transaction now always raises an
             error. GridFS does not support multi-document transactions.
  
          .. versionchanged:: 3.7
             Added the `disable_md5` parameter.
  
          .. versionchanged:: 3.1
             Indexes are only ensured on the first write to the DB.
  
          .. versionchanged:: 3.0
             `database` must use an acknowledged
             :attr:`~pymongo.database.Database.write_concern`
  
          .. seealso:: The MongoDB documentation on `gridfs <https://dochub.mongodb.org/core/gridfs>`_.
          """
          if not isinstance(database, Database):
              raise TypeError("database must be an instance of Database")
  
          database = _clear_entity_type_registry(database)
  
          if not database.write_concern.acknowledged:
              raise ConfigurationError("database must use acknowledged write_concern")
  
          self.__collection = database[collection]
          self.__files = self.__collection.files
          self.__chunks = self.__collection.chunks
  
      def new_file(self, **kwargs: Any) -> GridIn:
          """Create a new file in GridFS.
  
          Returns a new :class:`~gridfs.grid_file.GridIn` instance to
          which data can be written. Any keyword arguments will be
          passed through to :meth:`~gridfs.grid_file.GridIn`.
  
          If the ``"_id"`` of the file is manually specified, it must
          not already exist in GridFS. Otherwise
          :class:`~gridfs.errors.FileExists` is raised.
  
          :Parameters:
            - `**kwargs` (optional): keyword arguments for file creation
          """
          return GridIn(self.__collection, **kwargs)
  
      def put(self, data: Any, **kwargs: Any) -> Any:
          """Put data in GridFS as a new file.
  
          Equivalent to doing::
  
            try:
                f = new_file(**kwargs)
                f.write(data)
            finally:
                f.close()
  
          `data` can be either an instance of :class:`bytes` or a file-like
          object providing a :meth:`read` method. If an `encoding` keyword
          argument is passed, `data` can also be a :class:`str` instance, which
          will be encoded as `encoding` before being written. Any keyword
          arguments will be passed through to the created file - see
          :meth:`~gridfs.grid_file.GridIn` for possible arguments. Returns the
          ``"_id"`` of the created file.
  
          If the ``"_id"`` of the file is manually specified, it must
          not already exist in GridFS. Otherwise
          :class:`~gridfs.errors.FileExists` is raised.
  
          :Parameters:
            - `data`: data to be written as a file.
            - `**kwargs` (optional): keyword arguments for file creation
  
          .. versionchanged:: 3.0
             w=0 writes to GridFS are now prohibited.
          """
          grid_file = GridIn(self.__collection, **kwargs)
          try:
              grid_file.write(data)
          finally:
              grid_file.close()
  
          return grid_file._id
  
      def get(self, file_id: Any, session: Optional[ClientSession] = None) -> GridOut:
          """Get a file from GridFS by ``"_id"``.
  
          Returns an instance of :class:`~gridfs.grid_file.GridOut`,
          which provides a file-like interface for reading.
  
          :Parameters:
            - `file_id`: ``"_id"`` of the file to get
            - `session` (optional): a
              :class:`~pymongo.client_session.ClientSession`
  
          .. versionchanged:: 3.6
             Added ``session`` parameter.
          """
          gout = GridOut(self.__collection, file_id, session=session)
  
          # Raise NoFile now, instead of on first attribute access.
          gout._ensure_file()
          return gout
  
      def get_version(
          self,
          filename: Optional[str] = None,
          version: Optional[int] = -1,
          session: Optional[ClientSession] = None,
          **kwargs: Any
      ) -> GridOut:
          """Get a file from GridFS by ``"filename"`` or metadata fields.
  
          Returns a version of the file in GridFS whose filename matches
          `filename` and whose metadata fields match the supplied keyword
          arguments, as an instance of :class:`~gridfs.grid_file.GridOut`.
  
          Version numbering is a convenience atop the GridFS API provided
          by MongoDB. If more than one file matches the query (either by
          `filename` alone, by metadata fields, or by a combination of
          both), then version ``-1`` will be the most recently uploaded
          matching file, ``-2`` the second most recently
          uploaded, etc. Version ``0`` will be the first version
          uploaded, ``1`` the second version, etc. So if three versions
          have been uploaded, then version ``0`` is the same as version
          ``-3``, version ``1`` is the same as version ``-2``, and
          version ``2`` is the same as version ``-1``.
  
          Raises :class:`~gridfs.errors.NoFile` if no such version of
          that file exists.
  
          :Parameters:
            - `filename`: ``"filename"`` of the file to get, or `None`
            - `version` (optional): version of the file to get (defaults
              to -1, the most recent version uploaded)
            - `session` (optional): a
              :class:`~pymongo.client_session.ClientSession`
            - `**kwargs` (optional): find files by custom metadata.
  
          .. versionchanged:: 3.6
             Added ``session`` parameter.
  
          .. versionchanged:: 3.1
             ``get_version`` no longer ensures indexes.
          """
          query = kwargs
          if filename is not None:
              query["filename"] = filename
  
          _disallow_transactions(session)
          cursor = self.__files.find(query, session=session)
          if version is None:
              version = -1
          if version < 0:
              skip = abs(version) - 1
              cursor.limit(-1).skip(skip).sort("uploadDate", DESCENDING)
          else:
              cursor.limit(-1).skip(version).sort("uploadDate", ASCENDING)
          try:
              doc = next(cursor)
              return GridOut(self.__collection, file_document=doc, session=session)
          except StopIteration:
              raise NoFile("no version %d for filename %r" % (version, filename))
  
      def get_last_version(
          self, filename: Optional[str] = None, session: Optional[ClientSession] = None, **kwargs: Any
      ) -> GridOut:
          """Get the most recent version of a file in GridFS by ``"filename"``
          or metadata fields.
  
          Equivalent to calling :meth:`get_version` with the default
          `version` (``-1``).
  
          :Parameters:
            - `filename`: ``"filename"`` of the file to get, or `None`
            - `session` (optional): a
              :class:`~pymongo.client_session.ClientSession`
            - `**kwargs` (optional): find files by custom metadata.
  
          .. versionchanged:: 3.6
             Added ``session`` parameter.
          """
          return self.get_version(filename=filename, session=session, **kwargs)
  
      # TODO add optional safe mode for chunk removal?
      def delete(self, file_id: Any, session: Optional[ClientSession] = None) -> None:
          """Delete a file from GridFS by ``"_id"``.
  
          Deletes all data belonging to the file with ``"_id"``:
          `file_id`.
  
          .. warning:: Any processes/threads reading from the file while
             this method is executing will likely see an invalid/corrupt
             file. Care should be taken to avoid concurrent reads to a file
             while it is being deleted.
  
          .. note:: Deletes of non-existent files are considered successful
             since the end result is the same: no file with that _id remains.
  
          :Parameters:
            - `file_id`: ``"_id"`` of the file to delete
            - `session` (optional): a
              :class:`~pymongo.client_session.ClientSession`
  
          .. versionchanged:: 3.6
             Added ``session`` parameter.
  
          .. versionchanged:: 3.1
             ``delete`` no longer ensures indexes.
          """
          _disallow_transactions(session)
          self.__files.delete_one({"_id": file_id}, session=session)
          self.__chunks.delete_many({"files_id": file_id}, session=session)
  
      def list(self, session: Optional[ClientSession] = None) -> List[str]:
          """List the names of all files stored in this instance of
          :class:`GridFS`.
  
          :Parameters:
            - `session` (optional): a
              :class:`~pymongo.client_session.ClientSession`
  
          .. versionchanged:: 3.6
             Added ``session`` parameter.
  
          .. versionchanged:: 3.1
             ``list`` no longer ensures indexes.
          """
          _disallow_transactions(session)
          # With an index, distinct includes documents with no filename
          # as None.
          return [
              name for name in self.__files.distinct("filename", session=session) if name is not None
          ]
  
      def find_one(
          self,
          filter: Optional[Any] = None,
          session: Optional[ClientSession] = None,
          *args: Any,
          **kwargs: Any
      ) -> Optional[GridOut]:
          """Get a single file from gridfs.
  
          All arguments to :meth:`find` are also valid arguments for
          :meth:`find_one`, although any `limit` argument will be
          ignored. Returns a single :class:`~gridfs.grid_file.GridOut`,
          or ``None`` if no matching file is found. For example::
  
              file = fs.find_one({"filename": "lisa.txt"})
  
          :Parameters:
            - `filter` (optional): a dictionary specifying
              the query to be performing OR any other type to be used as
              the value for a query for ``"_id"`` in the file collection.
            - `*args` (optional): any additional positional arguments are
              the same as the arguments to :meth:`find`.
            - `session` (optional): a
              :class:`~pymongo.client_session.ClientSession`
            - `**kwargs` (optional): any additional keyword arguments
              are the same as the arguments to :meth:`find`.
  
          .. versionchanged:: 3.6
             Added ``session`` parameter.
          """
          if filter is not None and not isinstance(filter, abc.Mapping):
              filter = {"_id": filter}
  
          _disallow_transactions(session)
          for f in self.find(filter, *args, session=session, **kwargs):
              return f
  
          return None
  
      def find(self, *args: Any, **kwargs: Any) -> GridOutCursor:
          """Query GridFS for files.
  
          Returns a cursor that iterates across files matching
          arbitrary queries on the files collection. Can be combined
          with other modifiers for additional control. For example::
  
            for grid_out in fs.find({"filename": "lisa.txt"},
                                    no_cursor_timeout=True):
                data = grid_out.read()
  
          would iterate through all versions of "lisa.txt" stored in GridFS.
          Note that setting no_cursor_timeout to True may be important to
          prevent the cursor from timing out during long multi-file processing
          work.
  
          As another example, the call::
  
            most_recent_three = fs.find().sort("uploadDate", -1).limit(3)
  
          would return a cursor to the three most recently uploaded files
          in GridFS.
  
          Follows a similar interface to
          :meth:`~pymongo.collection.Collection.find`
          in :class:`~pymongo.collection.Collection`.
  
          If a :class:`~pymongo.client_session.ClientSession` is passed to
          :meth:`find`, all returned :class:`~gridfs.grid_file.GridOut` instances
          are associated with that session.
  
          :Parameters:
            - `filter` (optional): A query document that selects which files
              to include in the result set. Can be an empty document to include
              all files.
            - `skip` (optional): the number of files to omit (from
              the start of the result set) when returning the results
            - `limit` (optional): the maximum number of results to
              return
            - `no_cursor_timeout` (optional): if False (the default), any
              returned cursor is closed by the server after 10 minutes of
              inactivity. If set to True, the returned cursor will never
              time out on the server. Care should be taken to ensure that
              cursors with no_cursor_timeout turned on are properly closed.
            - `sort` (optional): a list of (key, direction) pairs
              specifying the sort order for this query. See
              :meth:`~pymongo.cursor.Cursor.sort` for details.
  
          Raises :class:`TypeError` if any of the arguments are of
          improper type. Returns an instance of
          :class:`~gridfs.grid_file.GridOutCursor`
          corresponding to this query.
  
          .. versionchanged:: 3.0
             Removed the read_preference, tag_sets, and
             secondary_acceptable_latency_ms options.
          .. versionadded:: 2.7
          .. seealso:: The MongoDB documentation on `find <https://dochub.mongodb.org/core/find>`_.
          """
          return GridOutCursor(self.__collection, *args, **kwargs)
  
      def exists(
          self,
          document_or_id: Optional[Any] = None,
          session: Optional[ClientSession] = None,
          **kwargs: Any
      ) -> bool:
          """Check if a file exists in this instance of :class:`GridFS`.
  
          The file to check for can be specified by the value of its
          ``_id`` key, or by passing in a query document. A query
          document can be passed in as dictionary, or by using keyword
          arguments. Thus, the following three calls are equivalent:
  
          >>> fs.exists(file_id)
          >>> fs.exists({"_id": file_id})
          >>> fs.exists(_id=file_id)
  
          As are the following two calls:
  
          >>> fs.exists({"filename": "mike.txt"})
          >>> fs.exists(filename="mike.txt")
  
          And the following two:
  
          >>> fs.exists({"foo": {"$gt": 12}})
          >>> fs.exists(foo={"$gt": 12})
  
          Returns ``True`` if a matching file exists, ``False``
          otherwise. Calls to :meth:`exists` will not automatically
          create appropriate indexes; application developers should be
          sure to create indexes if needed and as appropriate.
  
          :Parameters:
            - `document_or_id` (optional): query document, or _id of the
              document to check for
            - `session` (optional): a
              :class:`~pymongo.client_session.ClientSession`
            - `**kwargs` (optional): keyword arguments are used as a
              query document, if they're present.
  
          .. versionchanged:: 3.6
             Added ``session`` parameter.
          """
          _disallow_transactions(session)
          if kwargs:
              f = self.__files.find_one(kwargs, ["_id"], session=session)
          else:
              f = self.__files.find_one(document_or_id, ["_id"], session=session)
  
          return f is not None
  
  
  class GridFSBucket(object):
      """An instance of GridFS on top of a single Database."""
  
      def __init__(
          self,
          db: Database,
          bucket_name: str = "fs",
          chunk_size_bytes: int = DEFAULT_CHUNK_SIZE,
          write_concern: Optional[WriteConcern] = None,
          read_preference: Optional[_ServerMode] = None,
      ) -> None:
          """Create a new instance of :class:`GridFSBucket`.
  
          Raises :exc:`TypeError` if `database` is not an instance of
          :class:`~pymongo.database.Database`.
  
          Raises :exc:`~pymongo.errors.ConfigurationError` if `write_concern`
          is not acknowledged.
  
          :Parameters:
            - `database`: database to use.
            - `bucket_name` (optional): The name of the bucket. Defaults to 'fs'.
            - `chunk_size_bytes` (optional): The chunk size in bytes. Defaults
              to 255KB.
            - `write_concern` (optional): The
              :class:`~pymongo.write_concern.WriteConcern` to use. If ``None``
              (the default) db.write_concern is used.
            - `read_preference` (optional): The read preference to use. If
              ``None`` (the default) db.read_preference is used.
  
          .. versionchanged:: 4.0
             Removed the `disable_md5` parameter. See
             :ref:`removed-gridfs-checksum` for details.
  
          .. versionchanged:: 3.11
             Running a GridFSBucket operation in a transaction now always raises
             an error. GridFSBucket does not support multi-document transactions.
  
          .. versionchanged:: 3.7
             Added the `disable_md5` parameter.
  
          .. versionadded:: 3.1
  
          .. seealso:: The MongoDB documentation on `gridfs <https://dochub.mongodb.org/core/gridfs>`_.
          """
          if not isinstance(db, Database):
              raise TypeError("database must be an instance of Database")
  
          db = _clear_entity_type_registry(db)
  
          wtc = write_concern if write_concern is not None else db.write_concern
          if not wtc.acknowledged:
              raise ConfigurationError("write concern must be acknowledged")
  
          self._bucket_name = bucket_name
          self._collection = db[bucket_name]
          self._chunks: Collection = self._collection.chunks.with_options(
              write_concern=write_concern, read_preference=read_preference
          )
  
          self._files: Collection = self._collection.files.with_options(
              write_concern=write_concern, read_preference=read_preference
          )
  
          self._chunk_size_bytes = chunk_size_bytes
  
      def open_upload_stream(
          self,
          filename: str,
          chunk_size_bytes: Optional[int] = None,
          metadata: Optional[Mapping[str, Any]] = None,
          session: Optional[ClientSession] = None,
      ) -> GridIn:
          """Opens a Stream that the application can write the contents of the
          file to.
  
          The user must specify the filename, and can choose to add any
          additional information in the metadata field of the file document or
          modify the chunk size.
          For example::
  
            my_db = MongoClient().test
            fs = GridFSBucket(my_db)
            grid_in = fs.open_upload_stream(
                  "test_file", chunk_size_bytes=4,
                  metadata={"contentType": "text/plain"})
            grid_in.write("data I want to store!")
            grid_in.close()  # uploaded on close
  
          Returns an instance of :class:`~gridfs.grid_file.GridIn`.
  
          Raises :exc:`~gridfs.errors.NoFile` if no such version of
          that file exists.
          Raises :exc:`~ValueError` if `filename` is not a string.
  
          :Parameters:
            - `filename`: The name of the file to upload.
            - `chunk_size_bytes` (options): The number of bytes per chunk of this
              file. Defaults to the chunk_size_bytes in :class:`GridFSBucket`.
            - `metadata` (optional): User data for the 'metadata' field of the
              files collection document. If not provided the metadata field will
              be omitted from the files collection document.
            - `session` (optional): a
              :class:`~pymongo.client_session.ClientSession`
  
          .. versionchanged:: 3.6
             Added ``session`` parameter.
          """
          validate_string("filename", filename)
  
          opts = {
              "filename": filename,
              "chunk_size": (
                  chunk_size_bytes if chunk_size_bytes is not None else self._chunk_size_bytes
              ),
          }
          if metadata is not None:
              opts["metadata"] = metadata
  
          return GridIn(self._collection, session=session, **opts)
  
      def open_upload_stream_with_id(
          self,
          file_id: Any,
          filename: str,
          chunk_size_bytes: Optional[int] = None,
          metadata: Optional[Mapping[str, Any]] = None,
          session: Optional[ClientSession] = None,
      ) -> GridIn:
          """Opens a Stream that the application can write the contents of the
          file to.
  
          The user must specify the file id and filename, and can choose to add
          any additional information in the metadata field of the file document
          or modify the chunk size.
          For example::
  
            my_db = MongoClient().test
            fs = GridFSBucket(my_db)
            grid_in = fs.open_upload_stream_with_id(
                  ObjectId(),
                  "test_file",
                  chunk_size_bytes=4,
                  metadata={"contentType": "text/plain"})
            grid_in.write("data I want to store!")
            grid_in.close()  # uploaded on close
  
          Returns an instance of :class:`~gridfs.grid_file.GridIn`.
  
          Raises :exc:`~gridfs.errors.NoFile` if no such version of
          that file exists.
          Raises :exc:`~ValueError` if `filename` is not a string.
  
          :Parameters:
            - `file_id`: The id to use for this file. The id must not have
              already been used for another file.
            - `filename`: The name of the file to upload.
            - `chunk_size_bytes` (options): The number of bytes per chunk of this
              file. Defaults to the chunk_size_bytes in :class:`GridFSBucket`.
            - `metadata` (optional): User data for the 'metadata' field of the
              files collection document. If not provided the metadata field will
              be omitted from the files collection document.
            - `session` (optional): a
              :class:`~pymongo.client_session.ClientSession`
  
          .. versionchanged:: 3.6
             Added ``session`` parameter.
          """
          validate_string("filename", filename)
  
          opts = {
              "_id": file_id,
              "filename": filename,
              "chunk_size": (
                  chunk_size_bytes if chunk_size_bytes is not None else self._chunk_size_bytes
              ),
          }
          if metadata is not None:
              opts["metadata"] = metadata
  
          return GridIn(self._collection, session=session, **opts)
  
      def upload_from_stream(
          self,
          filename: str,
          source: Any,
          chunk_size_bytes: Optional[int] = None,
          metadata: Optional[Mapping[str, Any]] = None,
          session: Optional[ClientSession] = None,
      ) -> ObjectId:
          """Uploads a user file to a GridFS bucket.
  
          Reads the contents of the user file from `source` and uploads
          it to the file `filename`. Source can be a string or file-like object.
          For example::
  
            my_db = MongoClient().test
            fs = GridFSBucket(my_db)
            file_id = fs.upload_from_stream(
                "test_file",
                "data I want to store!",
                chunk_size_bytes=4,
                metadata={"contentType": "text/plain"})
  
          Returns the _id of the uploaded file.
  
          Raises :exc:`~gridfs.errors.NoFile` if no such version of
          that file exists.
          Raises :exc:`~ValueError` if `filename` is not a string.
  
          :Parameters:
            - `filename`: The name of the file to upload.
            - `source`: The source stream of the content to be uploaded. Must be
              a file-like object that implements :meth:`read` or a string.
            - `chunk_size_bytes` (options): The number of bytes per chunk of this
              file. Defaults to the chunk_size_bytes of :class:`GridFSBucket`.
            - `metadata` (optional): User data for the 'metadata' field of the
              files collection document. If not provided the metadata field will
              be omitted from the files collection document.
            - `session` (optional): a
              :class:`~pymongo.client_session.ClientSession`
  
          .. versionchanged:: 3.6
             Added ``session`` parameter.
          """
          with self.open_upload_stream(filename, chunk_size_bytes, metadata, session=session) as gin:
              gin.write(source)
  
          return cast(ObjectId, gin._id)
  
      def upload_from_stream_with_id(
          self,
          file_id: Any,
          filename: str,
          source: Any,
          chunk_size_bytes: Optional[int] = None,
          metadata: Optional[Mapping[str, Any]] = None,
          session: Optional[ClientSession] = None,
      ) -> None:
          """Uploads a user file to a GridFS bucket with a custom file id.
  
          Reads the contents of the user file from `source` and uploads
          it to the file `filename`. Source can be a string or file-like object.
          For example::
  
            my_db = MongoClient().test
            fs = GridFSBucket(my_db)
            file_id = fs.upload_from_stream(
                ObjectId(),
                "test_file",
                "data I want to store!",
                chunk_size_bytes=4,
                metadata={"contentType": "text/plain"})
  
          Raises :exc:`~gridfs.errors.NoFile` if no such version of
          that file exists.
          Raises :exc:`~ValueError` if `filename` is not a string.
  
          :Parameters:
            - `file_id`: The id to use for this file. The id must not have
              already been used for another file.
            - `filename`: The name of the file to upload.
            - `source`: The source stream of the content to be uploaded. Must be
              a file-like object that implements :meth:`read` or a string.
            - `chunk_size_bytes` (options): The number of bytes per chunk of this
              file. Defaults to the chunk_size_bytes of :class:`GridFSBucket`.
            - `metadata` (optional): User data for the 'metadata' field of the
              files collection document. If not provided the metadata field will
              be omitted from the files collection document.
            - `session` (optional): a
              :class:`~pymongo.client_session.ClientSession`
  
          .. versionchanged:: 3.6
             Added ``session`` parameter.
          """
          with self.open_upload_stream_with_id(
              file_id, filename, chunk_size_bytes, metadata, session=session
          ) as gin:
              gin.write(source)
  
      def open_download_stream(
          self, file_id: Any, session: Optional[ClientSession] = None
      ) -> GridOut:
          """Opens a Stream from which the application can read the contents of
          the stored file specified by file_id.
  
          For example::
  
            my_db = MongoClient().test
            fs = GridFSBucket(my_db)
            # get _id of file to read.
            file_id = fs.upload_from_stream("test_file", "data I want to store!")
            grid_out = fs.open_download_stream(file_id)
            contents = grid_out.read()
  
          Returns an instance of :class:`~gridfs.grid_file.GridOut`.
  
          Raises :exc:`~gridfs.errors.NoFile` if no file with file_id exists.
  
          :Parameters:
            - `file_id`: The _id of the file to be downloaded.
            - `session` (optional): a
              :class:`~pymongo.client_session.ClientSession`
  
          .. versionchanged:: 3.6
             Added ``session`` parameter.
          """
          gout = GridOut(self._collection, file_id, session=session)
  
          # Raise NoFile now, instead of on first attribute access.
          gout._ensure_file()
          return gout
  
      def download_to_stream(
          self, file_id: Any, destination: Any, session: Optional[ClientSession] = None
      ) -> None:
          """Downloads the contents of the stored file specified by file_id and
          writes the contents to `destination`.
  
          For example::
  
            my_db = MongoClient().test
            fs = GridFSBucket(my_db)
            # Get _id of file to read
            file_id = fs.upload_from_stream("test_file", "data I want to store!")
            # Get file to write to
            file = open('myfile','wb+')
            fs.download_to_stream(file_id, file)
            file.seek(0)
            contents = file.read()
  
          Raises :exc:`~gridfs.errors.NoFile` if no file with file_id exists.
  
          :Parameters:
            - `file_id`: The _id of the file to be downloaded.
            - `destination`: a file-like object implementing :meth:`write`.
            - `session` (optional): a
              :class:`~pymongo.client_session.ClientSession`
  
          .. versionchanged:: 3.6
             Added ``session`` parameter.
          """
          with self.open_download_stream(file_id, session=session) as gout:
              for chunk in gout:
                  destination.write(chunk)
  
      def delete(self, file_id: Any, session: Optional[ClientSession] = None) -> None:
          """Given an file_id, delete this stored file's files collection document
          and associated chunks from a GridFS bucket.
  
          For example::
  
            my_db = MongoClient().test
            fs = GridFSBucket(my_db)
            # Get _id of file to delete
            file_id = fs.upload_from_stream("test_file", "data I want to store!")
            fs.delete(file_id)
  
          Raises :exc:`~gridfs.errors.NoFile` if no file with file_id exists.
  
          :Parameters:
            - `file_id`: The _id of the file to be deleted.
            - `session` (optional): a
              :class:`~pymongo.client_session.ClientSession`
  
          .. versionchanged:: 3.6
             Added ``session`` parameter.
          """
          _disallow_transactions(session)
          res = self._files.delete_one({"_id": file_id}, session=session)
          self._chunks.delete_many({"files_id": file_id}, session=session)
          if not res.deleted_count:
              raise NoFile("no file could be deleted because none matched %s" % file_id)
  
      def find(self, *args: Any, **kwargs: Any) -> GridOutCursor:
          """Find and return the files collection documents that match ``filter``
  
          Returns a cursor that iterates across files matching
          arbitrary queries on the files collection. Can be combined
          with other modifiers for additional control.
  
          For example::
  
            for grid_data in fs.find({"filename": "lisa.txt"},
                                    no_cursor_timeout=True):
                data = grid_data.read()
  
          would iterate through all versions of "lisa.txt" stored in GridFS.
          Note that setting no_cursor_timeout to True may be important to
          prevent the cursor from timing out during long multi-file processing
          work.
  
          As another example, the call::
  
            most_recent_three = fs.find().sort("uploadDate", -1).limit(3)
  
          would return a cursor to the three most recently uploaded files
          in GridFS.
  
          Follows a similar interface to
          :meth:`~pymongo.collection.Collection.find`
          in :class:`~pymongo.collection.Collection`.
  
          If a :class:`~pymongo.client_session.ClientSession` is passed to
          :meth:`find`, all returned :class:`~gridfs.grid_file.GridOut` instances
          are associated with that session.
  
          :Parameters:
            - `filter`: Search query.
            - `batch_size` (optional): The number of documents to return per
              batch.
            - `limit` (optional): The maximum number of documents to return.
            - `no_cursor_timeout` (optional): The server normally times out idle
              cursors after an inactivity period (10 minutes) to prevent excess
              memory use. Set this option to True prevent that.
            - `skip` (optional): The number of documents to skip before
              returning.
            - `sort` (optional): The order by which to sort results. Defaults to
              None.
          """
          return GridOutCursor(self._collection, *args, **kwargs)
  
      def open_download_stream_by_name(
          self, filename: str, revision: int = -1, session: Optional[ClientSession] = None
      ) -> GridOut:
          """Opens a Stream from which the application can read the contents of
          `filename` and optional `revision`.
  
          For example::
  
            my_db = MongoClient().test
            fs = GridFSBucket(my_db)
            grid_out = fs.open_download_stream_by_name("test_file")
            contents = grid_out.read()
  
          Returns an instance of :class:`~gridfs.grid_file.GridOut`.
  
          Raises :exc:`~gridfs.errors.NoFile` if no such version of
          that file exists.
  
          Raises :exc:`~ValueError` filename is not a string.
  
          :Parameters:
            - `filename`: The name of the file to read from.
            - `revision` (optional): Which revision (documents with the same
              filename and different uploadDate) of the file to retrieve.
              Defaults to -1 (the most recent revision).
            - `session` (optional): a
              :class:`~pymongo.client_session.ClientSession`
  
          :Note: Revision numbers are defined as follows:
  
            - 0 = the original stored file
            - 1 = the first revision
            - 2 = the second revision
            - etc...
            - -2 = the second most recent revision
            - -1 = the most recent revision
  
          .. versionchanged:: 3.6
             Added ``session`` parameter.
          """
          validate_string("filename", filename)
          query = {"filename": filename}
          _disallow_transactions(session)
          cursor = self._files.find(query, session=session)
          if revision < 0:
              skip = abs(revision) - 1
              cursor.limit(-1).skip(skip).sort("uploadDate", DESCENDING)
          else:
              cursor.limit(-1).skip(revision).sort("uploadDate", ASCENDING)
          try:
              grid_file = next(cursor)
              return GridOut(self._collection, file_document=grid_file, session=session)
          except StopIteration:
              raise NoFile("no version %d for filename %r" % (revision, filename))
  
      def download_to_stream_by_name(
          self,
          filename: str,
          destination: Any,
          revision: int = -1,
          session: Optional[ClientSession] = None,
      ) -> None:
          """Write the contents of `filename` (with optional `revision`) to
          `destination`.
  
          For example::
  
            my_db = MongoClient().test
            fs = GridFSBucket(my_db)
            # Get file to write to
            file = open('myfile','wb')
            fs.download_to_stream_by_name("test_file", file)
  
          Raises :exc:`~gridfs.errors.NoFile` if no such version of
          that file exists.
  
          Raises :exc:`~ValueError` if `filename` is not a string.
  
          :Parameters:
            - `filename`: The name of the file to read from.
            - `destination`: A file-like object that implements :meth:`write`.
            - `revision` (optional): Which revision (documents with the same
              filename and different uploadDate) of the file to retrieve.
              Defaults to -1 (the most recent revision).
            - `session` (optional): a
              :class:`~pymongo.client_session.ClientSession`
  
          :Note: Revision numbers are defined as follows:
  
            - 0 = the original stored file
            - 1 = the first revision
            - 2 = the second revision
            - etc...
            - -2 = the second most recent revision
            - -1 = the most recent revision
  
          .. versionchanged:: 3.6
             Added ``session`` parameter.
          """
          with self.open_download_stream_by_name(filename, revision, session=session) as gout:
              for chunk in gout:
                  destination.write(chunk)
  
      def rename(
          self, file_id: Any, new_filename: str, session: Optional[ClientSession] = None
      ) -> None:
          """Renames the stored file with the specified file_id.
  
          For example::
  
            my_db = MongoClient().test
            fs = GridFSBucket(my_db)
            # Get _id of file to rename
            file_id = fs.upload_from_stream("test_file", "data I want to store!")
            fs.rename(file_id, "new_test_name")
  
          Raises :exc:`~gridfs.errors.NoFile` if no file with file_id exists.
  
          :Parameters:
            - `file_id`: The _id of the file to be renamed.
            - `new_filename`: The new name of the file.
            - `session` (optional): a
              :class:`~pymongo.client_session.ClientSession`
  
          .. versionchanged:: 3.6
             Added ``session`` parameter.
          """
          _disallow_transactions(session)
          result = self._files.update_one(
              {"_id": file_id}, {"$set": {"filename": new_filename}}, session=session
          )
          if not result.matched_count:
              raise NoFile(
                  "no files could be renamed %r because none "
                  "matched file_id %i" % (new_filename, file_id)
              )
  